The overwintering monarch population in Mexico again has dropped sharply, according to the numbers reported by World Wildlife Fund, Mexico. From a high of almost 21 hectares in 1996-97, the number has dropped to .67 hectares for the 2013-14 season.
Scientists in North America predicted the decrease, but that’s little comfort. Loss of habitat, the adoption of herbicide-tolerant crops and the increasing market for ethanol are the main causes for the ongoing monarch decline. Milkweed plants, the monarch larva’s sole food source, is considered a weed by agriculture.
Climate change also contributes to the butterfly’s plight as it makes it long migration to breeding grounds in spring and its return to overwintering colonies in Mexico in the fall. Cool, rainy summers affected reproductive success and early, harsh cold killed butterflies returning south.
In addition, mowing highway roadsides for tidiness — a common sight along freeways in North Texas — kills the native stands of milkweed plants, where monarch females lay eggs.
Monarch numbers will rebound, Monarch Watch scientists say, but only if the weather cooperates and there is enough milkweed to increase the population. “Given the current size of the overwintering population,” reports monarchwatch.org, “it is likely that it will take two to three years with relatively favorable breeding conditions for the population to attain such numbers.”
The only way citizens can help the monarchs survive is to plant milkweed — lots and lots of milkweed.